The transaminases aspartate aminotransferase (AST, SGOT) and alanine aminotransferase (ALT, SGPT) are released from hepatocytes following injury. If an injury is transient then the serum levels should decline to normal according to the protein kinetics.


If the decline in serum concentrations follows first order kinetics:


concentration at time T =

= (initial concentration in mg/dL) * EXP((-1) * k * (T in hours))


Half-Life in Hours

k value


16 hours



48 hours



The time required to decline to normal (serum concentration <= upper limit of normal reference range) is:


expected time to normalize in hours =

= LN((initial serum level) / (upper limit of normal reference range)) / k



• If the serum level has normalized within the expected time, then hepatic injury was transient.

• If the serum level has not normalized, then hepatic injury may be ongoing.


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